先看一眼
dmesg ，如果看到类似
brcmfmac_sdio mmc1:0001:1: Direct firmware load for <strong><em>.</em></strong> failed with error -2 的报错，使用 root 权限执行：
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modprobe -r brcmfmac apt-get install --reinstall firmware-brcm80211 pi-bluetooth cd /lib/firmware/brcm/ wget https://raw.githubusercontent.com/RPi-Distro/firmware-nonfree/master/brcm80211/brcm/brcmfmac43430-sdio.txt modprobe brcmfmac |
参考：rpi3 wifi issues